A typical milling machine table is elongated and has longitudinally extending inverted T-shaped slots to aid in mounting a workpiece holder, such as a vise, to the table. The T-slots also serve as collecting channels to return coolant to a collector mounted at one end of the table. A standard Bridgeport type milling machine table has one of two standard lengths, either 42" or 49" and a width of 9", with three parallel, spaced T-slots.
Milling machine tables of this type are susceptible to damage when tools such as wrenches, collets, files, drill chucks, parallels, etc. are placed on the top surface thereof. Such placement can result in nicks, burrs and indentations in the table which eventually destroy the accuracy of the milling operation. Moreover, metal chips often accumulate in the T-slots during milling, thus creating a difficult clean-up operation after and during use.
It is common among machinist to place a sheet of plastic, wood or metal on the top surface of the table in order to prevent build up of chips or dirt in the T-slots. However, covers of this type prevent coolant from being returned via the T-slots, and the coolant runs onto the floor, creating a safety hazard and poor working conditions. This excessive coolant loss also increases operating costs.
Tross U.S. Pat. No. 1,918,878 and Shorl U.S. Pat. No. 3,195,415 disclose elongated channel members which fit into the T-slots of machining tables. The channel members prevent cuttings or dirt from getting into the slots, and also have holes formed therethrough to enable coolant return flow into the T-slots. Suzuki U.S. Pat. No. 4,449,870 discloses a similar T-slot member which can be adjusted to accommodate T-slots of varying width. While such devices enable coolant to be returned via the T-slots, and further prevent the accumulation of matter in the T-slots, they do not provide adequate protection for the top surface of the milling machine table.
It is desirable to provide a single device which can be efficiently used with machine tools of varying table dimensions such that it isn't necessary to provide a comprehensive inventory of many different devices, one for each tool.
It is then an object of this invention to provide a protective device which simultaneously prevents filing or dirt accumulation in the T-slots, promotes return coolant flow through the T-slots, and protects the top surface of the table itself.
It is another object of this invention to provide a protective device which can be adapted to fit machine tools of varying table dimension.
Moreover, it is an object of this invention to provide a protective device which is reusable and adapted to be used for either standard length of slotted milling machine table.